It is well known to use various release aids, slip agents, internal and external lubricants, and various polymers as blends or on the surface of polyurethanes for reducing surface friction and increasing abrasion resistance.
For example, in Mobay Chemical Co., Technical Bulletin TIB 37-V13, "Semi-Self Lubricating Multrathane Types from Graphite," the advantages of using graphite as an additive are discussed. Also in U.S. Pat. No. 2,951,053 the use of molybdenum disulfide is disclosed. The use of these additives enables polyurethane elastomers to be used in applications requiring low friction. The elastomers become essentially self-lubricating and more abrasion resistant.